The present invention relates to surface treatment tools, and, more particularly, to attachment of a surface treatment tool such as a rotary brush to a rotational driver by using a kit. The present invention also relates to a bristle configuration for that rotary brush.
Numerous applications of rotary surface treatment tools are known. The tools often include a disk, plate or base portion which provides structural integrity for a surface treatment member. A surface treatment member extends from a face of the base. The surface treatment member can be, for instance, bristles of a brush, an abrasive such as sandpaper or grind stone, or a polishing buffer. A backing plate, face plate or other support structure may also be provided to provide support for the surface treatment member in use.
The surface treatment tool is used by attaching the tool to a rotational driver, such as a drill. For instance, a drill may have a threaded shaft which is rotated by the drill motor, and the surface treatment tool is attached by the threaded shaft. Alternatively, the drill may accept and rotate a bit, and the bit may be threaded. During use of the surface treatment tool, the surface treatment member is apt to wear or deteriorate, requiring occasional replacement with a new surface treatment member. Additionally, several different types of surface treatments may be performed with the same drill, requiring switching between different types of surface treatment members. For instance, sanding is often performed by sequential use of different sandpapers, starting with a coarse grained sandpaper and progressing through finer grained sandpapers. The drill may alternatively be used to perform completely different operations, on the same or different surfaces.
To reduce the cost of replacement or switching of surface treatment members, it is preferred that the rotary surface treatment tool be provided as a kit, with as much of the non-wearing support structure portion being reusable as possible. The used surface treatment member is replaced and the new surface treatment member is assembled with the rest of the kit and reattached to the rotational driver.
A wide variety of structures have been used to mount a surface treatment member to a support structure and/or shaft. For instance, the helically grooved drive button of U.S. Pat. No. 3,562,968 may be used. Other means of attachment, such as hook and loop fabric type fasteners of the type disclosed in U.S. Pat. Nos. 2,717,437, 3,009,235 or 5,077,870 or of the type commercially available under the trademark SCOTCHMATE from Minnesota Mining and Manufacturing Company, St. Paul, Minn., may be used alternatively or in conjunction with other attachment members in the kit. Many other more complicated structures have also been devised.
Some rotary surface treatment tool kits can provide attachment from the front, face or treatment side of the planar base. A tightening member extends through a hole in the surface treatment tool and places a compression force on the front (non-driven) side of the planar base. This compression force holds the surface treatment tool against a backing plate or hub. The tightening member may be made of metal and may have internal threads which mate with external threads on the shaft or bit. For instance, U.S. Pat. No. 3,166,877 shows such a kit.
Some of these prior attachment means include a point of relatively high shear stress for the attachment structure provided, leading to inelastic cycling and breakage problems of the attachment structure. Often the point of high shear stress in these attachment structures also carries a tension force which exacerbates the breakage problems. Attachment means such as hook and loop fabric type fasteners or adhesives can separate and not provide a reliable attachment force. Others of these attachment structures are structurally complicated and overly expensive to manufacture. Many of these attachment structures cannot be attached or tightened by hand and require tools such as wrenches which add expense to the kit and can be lost by the operator or user.
When a brush is used as the surface treatment member, the individual bristles may leave undesirable individual grooves or marks on the worked surface, referred to as "scribing". These grooves or marks occur particularly at stoppage of the drill or at removal of the brush from the worked surface. They may also occur at the starting of the drill, at contact of the brush to the worked surface, or when the brush is applied at an angle to the worked surface.